U.S. Pat. No. 2,751,821 illustrates and describes a typical broaching machine. Essentially such a machine comprises a frame, a broach carrying slide which is reciprocated between limits on ways secured to the frame. Also secured to the frame at approximately midway the slide travel limits is a knee on which is mounted a work supporting shuttle, which prior to the cutting pass of the broach brings the work-piece into operative position relative to the broach and at the termination of the cutting pass retracts the work-piece to clear the broach during the reverse or idle pass.
When exceptionally long broaching cuts are required the over-all length of the machine becomes prohibitive. The required length can be substantially halved by splitting the broach train into two parts and mounting both parts on the slide in spaced parallel relationship forming, in effect, two broach trains.
The work-piece is sequentially then brought into engagement with the first broach train, for what may be termed a rough cut, and then with the second broach train, for what may be termed a finish cut.
U.S. Pat. No. 2,870,688 discloses a by-level broaching machine wherein the work-piece is continuously maintained in the path of the broach trains. The rough cut broach train engages the work-piece on a forward pass of the broach slide and the second broach train engages the work-piece on the reverse pass of the broach slide. As a broaching operation imposes terrific forces on the work-piece, if both the forward and reverse passes of the broach slide are working passes, then, as recognized in U.S. Pat. No. 2,870,688, it is necessary to provide a back-up fixture capable of absorbing such forces to prevent distortion of the work-piece for the reverse as well as for the forward passes of the broach slide.